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Author Topic: Profile scale - can you add a round cowl ring?  (Read 1668 times)

Offline Dennis Toth

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Profile scale - can you add a round cowl ring?
« on: September 15, 2021, 07:52:05 AM »
I am looking at doing a simple profile SPAD WWI biplane and was wondering if a round ring cowl could be added under the profile scale rules?

Best,   DennisT

Offline Trostle

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Re: Profile scale - can you add a round cowl ring?
« Reply #1 on: September 15, 2021, 08:38:46 AM »
I am looking at doing a simple profile SPAD WWI biplane and was wondering if a round ring cowl could be added under the profile scale rules?

Best,   DennisT

A full round ring is allowed if it is no more than "one and one half (1.5) inches" for horizontally mounted engines and no more than "one half (.5) inch wider than the engine mounting lugs" for upright and inverted engines.

Keith

Offline Avaiojet

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Re: Profile scale - can you add a round cowl ring?
« Reply #2 on: September 15, 2021, 01:32:36 PM »
I am looking at doing a simple profile SPAD WWI biplane and was wondering if a round ring cowl could be added under the profile scale rules?

Best,   DennisT

Dennis,

Not much more work to do a full fuselage, and the results, well, there's no comparisons.

CB
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Offline pmackenzie

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Re: Profile scale - can you add a round cowl ring?
« Reply #3 on: September 18, 2021, 07:42:33 AM »
A full round ring is allowed if it is no more than "one and one half (1.5) inches" for horizontally mounted engines and no more than "one half (.5) inch wider than the engine mounting lugs" for upright and inverted engines.

Keith

Unless I am missing something, this seems like a long way to say "no" to full round cowl rings  :)

I guess if the scale of the model was such that the cowl ring was 1.5" diameter, it would be OK.
Either that, or get a motor with really wide mounting lugs :)
MAAC 8177

Offline Trostle

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Re: Profile scale - can you add a round cowl ring?
« Reply #4 on: September 18, 2021, 11:00:45 AM »


I guess if the scale of the model was such that the cowl ring was 1.5" diameter, it would be OK.


I think that is what I tried to say.  It can be done with small models powered by small engine(s) like the Cox .020 or .010.

This profile scale Hughes XF-11 is powered by two Cox .020 engines, 1/40 scale (0.3"=1').  Engine nacelles/nose rings are just less than 1.5".  The profile Republic XF-12 is to the same scale, same size engine nacelles with four Cox .010 engines.  Both full size aircraft used P&W 4360 engines.

Both won trophies at the Tucson 1/2A multi-engine profile scale contests which means that both flew the required 10 laps with all of their engines running.

For the record, the Hughes model tail booms and nose nacelle are within the required 1" maximum width allowed by the profile scale rules.

Keith
« Last Edit: September 21, 2021, 05:17:13 PM by Trostle »

Offline Dan McEntee

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Re: Profile scale - can you add a round cowl ring?
« Reply #5 on: September 21, 2021, 04:29:53 PM »
  Keith, I don't think I have ever seen that XF-11 before!! I don't think you published plans r article or anything but I don't even remember seeing it in any of the magazine coverages. The XF-12 is in equal awesomeness!! But I like the XF-11 better. I think one of the Moon brothers did a stunt model of it, which is interesting, but would loose a little character to me with out that sexy high aspect ration wing!
  How did it fly?
  Dan McEntee
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Offline Trostle

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Re: Profile scale - can you add a round cowl ring?
« Reply #6 on: September 21, 2021, 05:48:05 PM »
  Keith, I don't think I have ever seen that XF-11 before!! I don't think you published plans r article or anything but I don't even remember seeing it in any of the magazine coverages. The XF-12 is in equal awesomeness!! But I like the XF-11 better. I think one of the Moon brothers did a stunt model of it, which is interesting, but would loose a little character to me with out that sexy high aspect ration wing!
  How did it fly?
  Dan McEntee

Dan,

Thanks for the note.  Plans for either model have not been published.  The Brodak magazine sometimes had some coverage of the Tucson 1/2A multi-engine profile scale contests.  A picture of one of these (different years) might have been published or in the Model Aviation Scale column.

Both models flew but had a bit of a wing loading problem.  A little bit of whipping helped.  The XF-12 first flight was a bit tail heavy and was a challenge.  A piece lead in the nose wheel well helped that.  Landings (no throttles) downwind with an engine or some engines out worked out OK.

With these two models, the XF-11 model looks better than the XF-12 because its paint and finish is more realistic than the XF-12.  The Hughes XF-11 was painted a light gray, I have the FS number used by Hughes, and the panel lines were filled in so no panel lines were needed on the model.  Plus at this scale the Hughes is more realistic as the nose nacelle at 1" wide is almost scale and the rear portion of the booms aft of the wing are scale width and within the 1" max allowed by the rules.  On the XF-12 and its natural aluminum skin, I did not attempt to show panel lines (ran out of time), so lost a bit on realism and the aluminum Klass Kote did not turn out well.  Though the four nacelles were scale (also within the profile limits), the full size aircraft had a round fuselage cross section, so the 3" deep fuselage with its 1" width on the model, part of the appearance of the full scale aircraft was lost.

The Steve Moon Moon XF-11, done as a profile, (Flying Models June, 2007) was a very attractive model.  Because of the relatively low aspect ratio needed for a stunt design, the model misses somewhat the overall appearance of the full size aircraft.  This is one design which does not lend itself well to capturing the appearance of the full size aircraft when done as a stunt design with a "reasonable" aspect ratio suitable for CL Stunt.  Nevertheless, Steve Moon did a very nice job in capturing the appearance of the real aircraft.

Keith

Offline Dan McEntee

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Re: Profile scale - can you add a round cowl ring?
« Reply #7 on: September 21, 2021, 09:20:22 PM »
   Keith;
    Thanks for filling in the blanks. With the XF-11, you have to keep telling yourself that it wasn't a fighter but intended as a reconnaissance platform. I was just watching "The Aviator" today and during the scenes about the airplane, I just had to wonder "what if" they had developed it to it's full potential. . In reality, the U-2 wasn't very far behind it, and that would have limited it's life span, while the U-2 is still operational today!
  Thanks again,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Trostle

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Re: Profile scale - can you add a round cowl ring?
« Reply #8 on: September 22, 2021, 12:58:39 AM »
   Keith;
    Thanks for filling in the blanks. With the XF-11, you have to keep telling yourself that it wasn't a fighter but intended as a reconnaissance platform. I was just watching "The Aviator" today and during the scenes about the airplane, I just had to wonder "what if" they had developed it to it's full potential. . In reality, the U-2 wasn't very far behind it, and that would have limited it's life span, while the U-2 is still operational today!
  Thanks again,
   Dan McEntee

One thing about both of these airplanes.  They were powered by the 28 cylinder P&W 4360 rated at something like 3,000 HP at sea level.  The Republic XF-12 attained 462 MPH and was to have a range of over 4,200 miles.  The engine nacelles, filled with supercharging equipment were about the same length as the P-47.  Its first flight was in February, 1946, so the need for the long range reconnaissance in a prolonged Pacific war did not materialize.  There were proposals for a 40 passenger commercial airline version, but the cost of the aircraft and its operation made it impractical for commercial use given the surplus transport market at the end of the war.  There is a book titled "World's fastest Four-Engine Piston-Powered Aircraft" by Mike Machatg which gives a complete story with lots of pictures of the Republic XF-12, later designated the SR-12 Rainbow.  This book also gives a detailed account of the Hughes XF-11.  Lots of glossy pictures and well written.

Keith


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